GnRH agonist trigger in focus: does protocol choice between PPOS and antagonist strategies affect outcomes?

The aim of this study was to assess the effectiveness of the GnRHa trigger in the PPOS and GnRH antagonist protocols when using a GnRH agonist (GnRHa) trigger.

This retrospective cohort study conducted at Bahçeci Fulya IVF Center (January 2022-January 2024) included 802 patients undergoing ovarian stimulation with a starting dose of 300 IU gonadotropins using either a GnRH antagonist (n = 372) or PPOS protocol (n = 430), followed by a GnRHa trigger. The primary outcome was oocyte yield; secondary outcomes included pregnancy rates following the initial frozen embryo transfer (FET).

Baseline characteristics, including female age, BMI, and infertility duration, were comparable between groups. Although PPOS was associated with a shorter stimulation duration [10 (9-11) vs. 10 (10-11) days, p = 0.002], lower progesterone levels on trigger day [1.3 (0.74-1.48) vs. 1.5 (0.83-1.63) ng/ml, p = 0.002], and higher LH levels [4 (1.89-5.2) vs. 3.3 (1.4-4.1) IU, p < 0.001], oocyte yield and embryological outcomes were similar (p > 0.05 for all). Clinical pregnancy rates [63.6% vs. 63.8%, p = 0.95] and live birth rates [51.7% vs. 52.2%, p = 0.87] were also comparable. Regression analysis identified embryo quality (p = 0.003), but not stimulation protocol (p = 0.766), as a significant predictor of live birth.

PPOS and GnRH antagonist protocols provide similar oocyte yield and live birth rates following GnRHa trigger. These findings indicate that progestin use in PPOS is not associated with inferior clinical outcomes in the setting of GnRHa trigger; however, the underlying mechanisms and long-term efficacy require further investigations.